This patent document relates to operating virtual machines in a cloud computing service.
Cloud computing is network-based computing in which typically large collections of servers housed in data centers or “server farms” provides computational resources and data storage as needed to remote end users. Some cloud computing services allow entities, such as e-retailers, banks with online portals, and universities, to run server software applications (e.g., e-commerce server application, web server, or file server) in the cloud. Running applications in the cloud can include running processes on virtual machines that are provided by cloud service providers. Data centers can use load-balancing to deal out incoming data among two or more machines. A type of load-balancing can be performed by using a special-purpose Open Systems Interconnection model (OSI model) layer-2 hardware device residing between an incoming network connection and a private local area network that forms a contiguous layer-2 network, where the local network includes two or more machines that are interconnected via the contiguous layer-2 network. For example, such a machine can employ an Address Resolution Protocol (ARP) scheme to maintain availability of a virtual Media Access Control (MAC) address on a contiguous layer-2 network that corresponds to a load-balanced network address.